3, 3&#39;-dihalogen-dianthrahydroquinoneazine tetrasulphuric acid esters and process of making the same



Patented May 14, 1940 UNITED STATES 3,3 DIHALOGEN DIANTHRAHYDROQUI- NONEAZINE TETRASULPHURIG ACID ESTERS AND PROCESS OF MAKING THE SAME Otto Stallmann, South Milwaukee, Wis., assignor to E. I. du Pont de Ncmours & Company, .Wilmington, Del., a corporation of Delaware No Drawing. Original application August 24,

1936, Serial No. 97,647.

Divided and this application December 22, 1937, Serial No.

3 Claims.

This invention relates to the preparation of the leuco sulphuric acid ester of 2-bromo-3-aminoanthraquinone and to the conversion of this intermediate to 3,3 -dibromodianthrahydroquinoneazine (leuco tetrasulphuric acid ester of 3,3dibromo indanthrone).

This application is a division of my copending application U. S. Ser. No. 97,647 filed August 24, 1936. It is the object of this invention to prepare the tetrasulphuric acid ester of 3,3-dibromo dianthrahydroquinoneazine.

Although it was known that 2-amino-3-chloranthraquinone as well as the unsubstituted 2- aminoanthraquinone can be converted to the leuco sulphuric acid ester and that the resulting 3-chloro containing compound can be oxidized to the tetrasulphuric acid ester of dihydroanthraquinoneazine, it was early found that the same procedure could not be employed for the preparation of the corresponding 3,3-dibromo indanthrone compound.

The 2-amino-3-chloroanthraquinone hereto fore used as the starting material in the preparation of the leuco-sulphuric acid esters of 2- amino-3-chloroanthraquinone is diificult to prepare, and the Z-amino-3-bromoanthraquinorie cannot be solubilized by the procedure ordinarily used for solubilizing the Z-amino-S-chloroanthraquinone. I have found that the much more readily available 1,3-dihalogen-Z-aminoanthraquinones can be converted directly and in high yields to the sulphuric acid esters of the corresponding Z-amino 3 halogen anthraquinone when the nitrogen group has been completely protected by acidyl or alkyl radicals and the resulting compound suspended or dissolved in pyridine and treated with sulphur trioxide, oleum, chlorosulphonic acid or the pyridine sulphur trioxicle compound obtainable by the reaction of sulphur trioxide on pyridine. The reaction is carried out in the presence of a metal, such as copper or zinc, at temperatures of from 40 to 120 C., until a test sample shows complete solubility of the reaction product in dilute caustic soda. The halogen in the l-position is completely eliminated and the leuco-sulphuric acid ester compound which is formed can be readily oxidized to the dihalogen-dianthrahydroquinone azine tetrasulphuric acid ester by the usual methods.

This process is suitable not only for the preparation of 3,3-dichloro-dianthrahydroquinone azine tetrasulphuric acid ester, but it is particularly applicable to the preparation of 3,3- dibromo-dianthrahydroquinohe azine tetrasulphuric acid ester, which compound has not been disclosed in the prior art.

The following examples are given to more fully illustrate the invention. The parts used are by by weight.

Example 1 100 parts dry, pulverized 1,3-dibromo-2-acetylaminoanthraquinone (obtainable by acetylating 1,3-dibromo-2-aminoanthraquinone in nitrobenzene solution with excess acetic anhydride at Mil-150 C. and having a melting point of 264-266" C.) are suspended in 500 parts dry pyridine, to which 250 parts pyridine-sulphur trioxide (obtainable by reacting dry pyridine with S03) have been added. The mass is then heated to -90 C. at which temperature 80 parts of copper bronze are added slowly and uniformly over a period of one-half hour, while agitating at -95 C. The mass is stirred for two and onehalf hours, at 90-95 C. and then cooled to below 40 C. The reaction product may be isolated by any one of the known methods, that are usually employed for the isolation of the leuco-sulphuric acid esters of the corresponding chloroderivative; for instance, by pouring the mass into 2000 parts of a dilute soda ash solution containing 160 parts NazCOs, stirring for one-half hour and distilling oh the pyridine in vacuo. The residual mass is then further treated with parts lime and 10 parts caustic soda and freed of copper salts by filtration. The filtrate may be salted with potassium carbonate, until the precipitation of the dipotassium salt of the disulphuric acid ester of 2-acetylamino-3-bromoanthrahydroquinone is complete. melt may also be poured into an excess of dilute caustic soda, the pyridine may then be distilled off in vacuo, the residual mass filtered free of copper salts and the filtrate evaporated to dryness. The product is very similar in all physical properties to the corresponding known chloroderivative, except that the alkali metal salts are somewhat less soluble in concentrated inorganic salt solution. Caustic alkalies at 90-100 C. hydrolyzed the product to the dipotassium salt of the disulphuric acid ester of 2-'amino-3-bromoanthrahydroquinone, which may be crystallized from a hot 10% KOH solution in quite large yellow needles, by cooling. Acid oxidizing agents,

such as nitrous acid, acid and copper sulphate or alkali metal chlorates, convert the products into 2-amino-3-bromoanthraquinone and Z-acetylamino-3-bromoanthraquinone, respectively.

Example 2 100 parts 1,3-dibromo-2-acetylaminoanthraquinone (which also may be obtained by treating the amino body in monohydrate solution with excess acetic anhydride) are suspended in 500 parts Alternatively, if desired, the pyridine dry pure pyridine (B. P. 115-117 0.), to which 130 parts oleum (of 60% S03 content) have been added. The mass is heated to 80 C. and at that temperature 100 parts of copper powder are slowly added over a period of one-half hour. The mass is further heated to 85 C. for about one hour or until a test portion when diluted with very dilute caustic soda shows complete solubilization. The mass is then cooled and the reaction product is isolated by any one of the methods described in Example 1. The product is identical with the reaction product of Example 1.

Example 3 The reaction is carried out as described in Example 1, exceptthat instead of 80 parts copper bronze, 50 parts copper powder, together with 50 parts zinc powder, are employed. The reaction is completed in two and one half hours and at 90-95 C. and the reaction product is found to be identical with the product of Example 1.

Example 4 115 parts 1,3-dibromo-2-benzoylaminoanthraquinone (obtainable by benzoylating 1,3-dibromo- Z-aminoanthraquinone in nitrobenzene with excess benzoyl chloride) are suspended in 1000 parts dry pyridine to which 260 parts oleum (60%) have been added. The mass is heated to 75 C. and 25 parts copper powder are then added, whereupon the mass becomes quite thick and the temperature rises to about 80 C. An additional 75 parts of copper powder are added and the mass is stirred at 80 C. for twentyfive minutes, whereupon the mass becomes quite thin and the reaction product appears to be in solution. At this point the mass is cooled to C. and poured into 10,000 parts of a 6% soda ash solution. After stirring for fifteen minutes and settling for one-half hour, the clear water layer is decanted off and the residue is stirred for fifteen minutes with 1000 parts of a 10% potassium hydroxide solution. 25 parts of sodium bicarbonate are added and the pyridine is distilled off under high vacuum. The residual mass is diluted to a total volume of 1650 parts with water and filtered at 50 C. Upon cooling the filtrate to room temperature, the reaction product precipitates out of solution and the precipitation may be completed by the addition of parts potassium carbonate (bringing the K2003 concentration to 5%). The reaction product, which may be filtered off and dried, is the dipotassium salt of the disulphuric acid ester of 2-benzoylamino- 3-bromoanthrahydroquinone, which is much less soluble in salt solution than the corresponding acetyl derivative. Acid oxidizing agents convert the product into 2-benzoylamino-3-bromoanthraquinone of a melting point range of 258-260 C. 10% caustic solutions hydrolyze the benzoyl compound on heating for one hour to C., giving the leuco-sulphuric acid ester of the free amino body in the form of its alkali metal salt.

Example 5 40 parts 1.3-dibromo-Z-acetyl-N-monomethylanthraquinone (having a melting point of 203-205 C. and obtained by acetylating 1,3-dibromo 2 N monomethylaminoanthraquinone, which in turn was obtained by reacting the amino body with formaldehyde in concentrated sulphuric acid or oleum, as describedin the copending application No. 37,329 by J. Deinet, in 500 parts of a mixture of equal parts glacial acetic acid and acetic anhydride) are suspended in 300 parts dry pyridine, to which 60 parts oleum (65% S03 content) have been added.' The mass is heated to 80 C. and 40 parts copper powder are added at 80-85 C. The mass is then further stirred for two hours at 80-85 C. and poured into 5000 parts of ice and water containing 75 parts soda ash. After stirring for twenty minutes, the precipitate is allowed to settle, the clear water layer is siphoned off and the residue is treated with 500 parts of a 10% caustic soda solution. The pyridine is then removed by a vacuum steam distillation and the residual mass is filtered free of copper salts. The filtrate is salted with enough potassium carbonate to obtain a 20% K2003 solution and the precipitated reaction product is filtered off and hydrolyzed in a solution of 15% KOH for one hour at 90 C. Upon cooling, the reaction product is obtained in yellowish needles. Theproduct is the dipotassium salt of the disulphuric acid ester of Z-N-monomethylamino- 3-bromoanthrahydroquinone which upon treatment with acid oxidizing agents, such as nitrous acid, is converted into 2-N-monomethylamino-3- bromoanthraquinone.

All the reaction products of the above examples may be oxidized, after hydrolysis to the free amino bases, in alkaline solutions with strong oxidizing agents, such as lead peroxide, alkali metal, hypochlorite, potassium ferricyanide or electrolytically, by the methods described in literature, for the preparation of the leuco-tetrasulphuric acid ester of 3,3-dibromoindanthrone from the 2-amino-3-bromoanthrahydroquinonedisulphuric acid ester, as further illustrated by the following examples.

Example 6 An amount of the potassium salt of 2-amino- 3 bromoanthrahydroquinone disulphuric acid ester (as obtained in Examples 1, 2, 3, or 4) equivalent to 44 parts of (regenerated) 2-amino- 3-bromoanthraquinone are dissolved at 90 C. in 90 parts of a 10% KOH solution, and there are then added under agitation '75 parts lead peroxide (PbO2) and the mass is stirred for one hour at 90 C. The mass is then filtered at 90 C. and to the filtrate are added 50 parts potassium hydroxide. Upon cooling, the reaction product crystallized out of solution. It is the tetra-potassium salt of the tetrasulphuric acid ester of 3,3-dibromodianthrahydroquinone azine of the probable formula.

oso31 Kola-o o souc N I o-souc The product may be further purified by redissolving parts of the dry product in 1000 parts water and precipitating by adding at 70-80 C. 50 parts KOH and 500 parts methyl alcohol. Upon cooling the solubilized indanthrone dyestuff is obtained in golden-yellow colored crystals, which resemble in general physical and chemical properties the corresponding chloro-derivative, when the latter is purified in an analogous manner. The product can be printed, dyed, and padded by the same methods as are commonly employed for the corresponding chloro-derivative. It yields shades of equal brightness, but somewhat more greenish-blue in tone in comparison with the shades obtained from the tetrasulphuric acid ester of leuco-3,3-dichloroindanthrone. Acids convert the yellow product into the disulphuric acid ester, which is of a purple color, sparingly soluble in water. Acid oxidizing agents convert the product into 3,3-dibromoindanthrone of very high purity.

Example 7 25 parts of the disoda salt of 2-acetylamino-3- bromoanthrahydroquinone-disulphuric acid ester (as obtained by pouring the pyridine melt into dilute caustic soda according to one of the alternative methods described in Example 1)- are dissolved in 250 parts dilute caustic soda solution containing 20 parts NaOH. The solution is boiled for one-half hour in order to hydrolyze the acetyl group and 0.5 part potassium ferricyanide is then added. The solution is then cooled to (SO-65 C. and while agitating at this temperature an electric current is allowed to pass through the solution, using iron electrodes and maintaining a potential of 6 volts and a current of 2.7 and 2.8 amperes. The oxidation is continued for about three hours or until a test portion shows the reaction mass to be free of unchanged Z-amino-B-bromoanthraquinone body. The solution is then filtered at 65 C. and to the filtrate are added, at 70-80 0., 65 parts potassium hydroxide and parts methyl alcohol. Upon cooling, the reaction product crystallizes out of solution in golden-yellow crystals, which are identical to the purified reaction product of the previous example.

Example 8 10 parts of the dipotassium salt of 2-N-monomethyl-amino-3-bromoanthrahydroquinone di sulphuric acid ester (as obtained in Example 5) are heated at C. in a 10% solution of KOH, to which 10 parts lead peroxide have been added. After heating for fifteen minutes the mass is filtered. 'Ihe filtrate is a solution of the potassium salt of the tetrasulphuric acid ester of leuco-3,3'- dibromo-N-dimethyl-indanthrone together with some impurities. It dyes cotton in the same yellowish shades as the corresponding leuco-sulphuric acid esters of the 3,3-dibromoindanthrone. Acid oxidizing agents in the cold convert this yellow dyeto the blue indanthrone com pound which is identical with the indanthrone dyestuff obtained from 1,3-dibromo-2-N-monomethylaminoanthraquinone obtained according.

to the method described in the copending appli cation No. 37,329 by J. Deinet. The methyl groups therefore remain attached to the nitrogen atoms during the solubilization and oxidation treatment.

It will be well understood that many modifications may be employed in my novel solubilization reaction. Thus the amounts of solvent (pyridine) used may be varied over very wide limits, as long as enough solvent is used to render the mass stirrable. It has also been found that the temperature at which the reaction is carried out may be varied to some extent, provided that on the one hand the temperature is high enough to permit the reaction to be completed within a reasonable time, and on the other hand not high enough to attack the halogen in the 3-position. The preferred temperature limits, thus defined, are usually between 40 and 120 C. Wider limits may be permissible, depending upon the nature of the compound to be solubilized. In general, it has been found that more stringent conditions, such as higher temperatures or longer reaction time may be safely employed, when working with 3-chloro-2-aminoanthraquinone bodies, whereas the corresponding bromo-derivatives tend to lose some of the halogen, even in the 3-positions, when the temperature is raised above C. and the heating is continued for more than one to two hours.

The order of charging the components into the reaction vessel may be further modified, for instance, by charging an intimate mixture of the dry, pulverized 1,3-dihalogen-2-N-substituted aminoanthraquinones with copper powder into the pyridine melt at the reaction temperature.

Other N-substituents than those mentioned by which the amino group is protected and which subsequently may be removed prior to the oxidation of the indanthrone color may be employed, as will be readily understood by those skilled in the art. I

Instead of using the ketonic anthraquinone bodies as starting materials, the isolated dry leuco derivatives (obtainable, for instance, from the alkaline hydrosulphite vats by known procedures or by catalytic hydrogenation, according to the method described in U. S. Patent 1,829,840) may be employed, but metals must be used in the solubilization according to this invention, to effect the replacement of the alpha halogen by hydrogen.

I claim:

1. In the process for preparing the alkali metal salts of tetrasulphuric acid esters of 3,3'-dihalogen-dianthrahydroquinoneazines, the steps which comprise reacting a 1,3-dihalogen-2- aminoanthraquinone in which the amine group is protected by substituents of the class consisting of alkyl and acidyl groups, in pyridine, with a compound of the class consisting of sulphur trioxide, oleum, chlorosulphonic acid and the pyridine sulphur trioxide compound obtainable by reacting sulfur trioxide and pyridine, in the presence of copper, at a temperature of from about 40 to C., isolating the resulting compound as the alkali metal salt, hydrolyzing the same to the free amine and reacting it in an alkaline solution with an oxidizing agent, to convert it to the 3,3-dihalogen-dianthrahydroquinoneazine tetrasulphuric acid ester alkali metal salt.

2. In the process for preparing the alkali metal salts of tetrasulphuric acid esters of 3,3'-dibromodianthrahydroquinoneazine, the steps which comprise heating 1,3-dibromo-2-aminoanthraquinone,

in which the amine group is protected by sub-- stituents of the class consisting of alkyl and acidyl groups, in pyridine with a sulphonating agent of the class consisting of sulphur trioxide, oleum, chlorosulphonic acid and the pyridine sulphur trioxide compound obtainable by reacting sulphur trioxide and pyridine in the presence of copper, at a temperature not materially above 100 C., until solubilization is complete, isolating the resulting compound as the alkali metal salt, hydrolyzing the same to the amine and reacting it in an alkaline solution with an oxidizing agent to convert it to the 8,3-dibromo-dianthrahydroquinoneazine tetrasulphuric acid ester alkali metal salt.

3. As a new compound, 3,3'-dibromo-dianthrahydroquinoneazine tetrasulphuric acid ester tetra-alkali metal salt.

OTTO STALLMANN. 

